Genetically-controlled MRI contrast agents for functional brain imaging

了解大脑如何控制行为是当今突出的科学问题之一。 研究行为的神经机制最需要的方法是将非侵入性和 具有细胞记录技术的精确度的磁共振成像(MRI)的全脑覆盖- 电生理学和荧光显微镜之类的技术。在这里，我们建议开发一套新的Neu- 接近这一理想的成像技术。这些方法依赖于基于蛋白质的传感器的使用 报告神经功能的各个方面，并可能针对特定的细胞或细胞类型。与蛋白质传感器不同 以前开发的用于光学成像的传感器，我们建议创建的传感器将结合MRI对比度 毒剂，这意味着它们可以在整个完整的大脑中进行监测；基因靶向将允许神经 被定义的“电路元件”的活动将被识别并被整合到大脑功能的解释模型中。 在前两个具体目标中，我们建议形成和应用遗传编码的钙敏感对比。 以铁储存蛋白铁蛋白(Ft)为基础的试剂。我们的初步数据和最近公布的结果 表明该设计的可行性，一旦在细胞培养中得到验证，我们将在大鼠身上进行测试。FT- 以传感器为基础的传感器可能不能提供足够的灵敏度来对神经元的稀疏或细微变化进行功能成像 然而，Ronal生理学。为了解决这个问题，我们在目标3-4中建议开发第二个基因- 一种受控系统，在该系统中，神经元活动的标志物被酶转导和放大到RO-R中。 可使用强大的外源性造影剂读出的胸部信号。这个计划是一项雄心勃勃的计划 而高影响力的努力，一旦完成，将改变研究人员研究大脑的方式。这个 Pi和他的实验室拥有不同的经验、有效合作的记录和冒险精神 精神，将使他们能够引入新一代大脑测量和经验方法 神经科学。

Understanding how the brain controls behavior is one of the outstanding scientific problems of today. The methods most needed to study neural mechanisms of behavior will combine the noninvasiveness and whole-brain coverage of magnetic resonance imaging (MRI) with the precision of cellular recording tech- niques like electrophysiology and fluorescence microscopy. Here we propose to develop a new set of neu- roimaging techniques that approach this ideal. The methods rely on the use of protein-based sensors that report aspects of neural function and may be targeted to specific cells or cell types. Unlike protein sensors developed previously for optical imaging, the sensors we propose to create will incorporate MRI contrast agents, meaning that they can be monitored across entire, intact brains; genetic targeting will allow neural activity of defined “circuit elements” to be identified and integrated into explanatory models of brain function. In the first two Specific Aims, we propose to form and apply genetically-encoded calcium-sensitive contrast agents based on the iron storage protein ferritin (Ft). Our preliminary data and recently published results indicate feasibility of the design, which we will test in rats once it has been validated in cell culture. Ft- based sensors may not offer enough sensitivity for functional imaging of sparse or subtle changes in neu- ronal physiology, however. To address this, we propose in Aims 3-4 to develop a second genetically- controlled system in which markers of neuronal activity are transduced and amplified by enzymes into ro- bust signals that may be read out using powerful exogenous contrast agents. This program is an ambitious and high-impact endeavor that, once accomplished, will change the way researchers study the brain. The PI and his laboratory have the diversity of experience, record of effective collaborations, and risk-taking spirit that will allow them to introduce a new generation of brain measurements and empirical approaches in neuroscience.